Resolved UnsupportedOperation Exception

Collections.unmodifiableMap(kerning)

getKerning returns a unmodifiableMap but your code modifies it.

(AngelFontCode:160) info.getKerning().put((char) second, amount);
UnsupportedOperation Exception
Merge pull request #232 from Alchemist0823/1.4

Resolved UnsupportedOperation Exception